Replaceable seat insert and process of making

ABSTRACT

This invention concerns a replaceable insert for flare-edged, fully supported type chairs that combines the features of a rigid yet flexible base, a cushion, a nonwrinkling, nontearable cover, and resilient edge clamping means in one integral unit and to a novel method of making the insert. This seat insert is characterized by low manufacture and material costs as well as the absence of metal fasteners and other adjustable implements thus eliminating special installation skills and tools.

United States Patent Grant et al.

[ 51 Mar. 7, 1972 [54] REPLACEABLE SEAT INSERT AND PROCESS OF MAKING[721 inventors: Bernard Carrington Grant, Sylvania; John F. Reilly,Toledo, both of Ohio [73] Assignee: The General Tire 8: Rubber Company[22] Filed: Aug. 13, 1970 [21] Appl. No.: 63,371

[52] [1.8. CI ..297/2l9, 297/457, 297/459, 297/D1G. l

[5 1] Int. Cl. ..A47c 27/16, A47c 3/00 [58] Field of Search ..297/DIG.1, D16. 2, 218, 219, 297/228, 229, 445, 449, 452, 455-459; 156/153;5/353.1353.3

[56] References Cited UNITED STATES PATENTS 2,738,835 3/1956 Eames..297/456 2,760,562 8/1956 Fisher ..297/DlG. 1 3,061,374 10/1962Grosfillex... ..297/457 X 3,174,797 3/1965 Neufeld..... ..297/2183,281,185 10/1966 Albinson et al.... ..297/452 3,314,721 4/1967 Smith..297/457 X 3,515,430 6/1970 Nelson ..297/219 X 3,519,308 7/1970 Kasmanet al. ..297/452 Primary Examiner-Casmir A. Nunberg Attorney-Frank C.Rote, Jr. and Denbigh S. Matthews [57] ABSTRACT This invention concernsa replaceable insert for flare-edged, fully supported type chairs thatcombines the features of a rigid yet flexible base, a cushion, anonwrinkling, nontearable cover, and resilient edge clamping means inone integral unit and to a novel method of making the insert. This seatinsert is characterized by low manufacture and material costs as well asthe absence of metal fasteners and other adjustable implements thuseliminating special installation skills and tools.

11 Claims, 3 Drawing Figures PATENTEDMAR 1:912

B 3 mm u l 4 a a" MK W 3 Wm& I WW a u INVENTORS. GRANT REILLY B. C. J. F

ATTORNEY REPLACEABLE SEAT INSERT AND PROCESS OF MAKING BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to the fieldof upholstery. More particularly, this invention relates to the field ofreplaceable upholstery parts, namely, replaceable seat inserts forchairs.

2. DESCRIPTION OF THE PRIOR ART In the field of upholstery for chairsand other support devices, there exist many types and designs ofreplaceable upholstery parts therefore such as seat inserts. There areinserts that contain rigid edges that snap into recesses in the chairsupport (US. Pat. Nos. 2,901,028 and 3,019,051); there is the cushiontype of insert having a rim-containing metal or rope for tightening overthe perimeter of the chair (U.S. Pat. No. 3,174,797); there are cushioninserts having rims to be bolted or clamped to the chair frame (US. Pat.Nos. 3,182,377 and 2,186,301); there is the cushion type of insert thatis pinched into narrow hook-shaped channels in the chair frame (US. Pat.No. 3,126,229); there are cushion inserts that are wedged and glued tothe chair frame (U.S. Pat. Nos. 2,233,986 and 3,273,178); there is thecushion insert that is glued and/or resiliently clamped (US. Pat. No.3,281,185); there is the cushion insert that has a cover which containsintegral resilient edge clamping means (US. Pat. No. 3,216,029); andthere is the rigid chair insert that has integral split tube clampingmeans (U.S. Pat. No. 3,061,374). All of these various types ofreplaceable upholstery inserts have certain disadvantages. Specifically,they are either too costly to manufacture in large quantities or requireskilled or semiskilled technicians to effect their replacement in thechair.

The rising crime rate has in large part taken the form of vandalism ofpublic and private property. This has manifested itself to a largeextent in the slashing and cutting of pieces of public furniture such aschairs and seats in public transportation vehicles and demolishing ofchairs in bus, airport, and train stations. Such damage requires thatthe replacement upholstery insert be not only installable by nonskilledworkers, but of relatively low cost.

If the chair support recesses are damaged by vandals, the snap-in typeof cushions become difficult to insert in the chair; replaceable insertshaving perimeter-tightening devices and bolts tend to tear at the coverlayer and, in addition, require at least semiskilled personnel to effectinstallation; cushion inserts that are pinched into place tend to comeloose during heavy usage, such as by a heavy flow of occupant traffic ina bus station; glued and wedged seat inserts require that the old gluebe scraped away and that a period of time be set aside for the new glueto set or dry; many of the resilient edge clamping means require sharphook-shaped supports that are easily damaged and ifmade from metal tendto rust and corrode; and rigid seat inserts containing split tubesupport means for fixing to a tubular frame are excessively expensive asthe whole chair support must be replaced. The present trend of usinginexpensive plastic films and sheets in construction of replaceableinserts has proved unsuccessful to a large extent because of thecombined properties of most plastics known as memory" andstretchability;" many rigid plastic pieces undergo slow deformation atroom temperature to their original configuration (hence, a memory) andmany soft plastic cushion covers stretch upon usage and become wrinkledand lose their aesthetic appeal.

This invention is a replaceable seat insert for a flare-edged, fullysupport type chair that overcomes to a great extent these aforementionedproblems. The cost of the insert is low, both in terms of material andlabor required to manufacture it; the insert may be installed on thechair by nonskilled workers; and the insert retains its shape and smoothsurface over a wide range of temperatures and under heavy usage.

Therefore, the main object of this invention is a replaceable seatinsert for a flare-edged, fully supported type of chair that is low costand easily put into use. Other objects include a unique method ofmanufacturing said insert combining a number of different polymericmaterials in a unique combination utilizing inexpensive bonding andother retaining means to effect construction of the insert at a lowcost. These and other objects will become more apparent upon reading theDescription of the Preferred Embodiment in conjunction with the drawingsattached hereto.

SUMMARY OF THE INVENTION This invention concerns a replaceable seatinsert for a flareedged, fully supported type chair comprising incombination a rigid yet flexible base conforming to the contour and tothe nonflared outline of the chair positioned by one surface against thechair support, the base having at least one aperture in the deepestdrawn area thereof; a cushion layer comprising a relatively thin layerof open-celled flexible foam adhered to the opposite surface of thebase; a nonwrinkling and nontearable cover layer comprising afabric-backed expanded sheet of flexible polymeric material adhered byits fabric-backed side to the cushion layer, and being uniformlyslightly larger in area than the base so as to provide an overlappingstrip of material extending slightly beyond the periphery of the baseand cushion layer; and resilient clamping means joined to theoverlapping strip of cover layer for anchoring engagement with the flareedge of the chair support. This invention also concerns a method ofmaking the aforedescribed seat insert.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional side view of atypical flare-edged, fully supported type chair showing the replaceableseat insert of this invention in position.

FIG. 2 is a cross-sectional view of the flared edge of the chair of FIG.1 and in particular shows the insert of this invention positionedthereon.

FIG. 3 is a cross-sectional view of one embodiment of the resilientclamping means of this invention in its relaxed condition.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawingswherein like elements are identified by like numerals throughout thethree figures, FIG. I shows in cross section a typical flare-edged,fully supported type chair and comprises in combination a pedestal 1that surrounds a large portion of the seat and back of the chair and isconnected to or integral with leg 3 that is in turn connected to orintegral with platform 5 for mounting or resting directly on floor 7.Pedestal 1, leg 3, and platform 5 may be made of virtually any solidmaterial such as metal, wood, plaster, plastic, or concrete; usually aplastic or concrete is used. Full chair support 9 is positioned onpedestal 1 and is a contoured unitary structure of a size to include theback and seat portion of a typical chair. Full chair support 9 may bemade of a number of different rigid materials such as wood, metal, andplastic; however, the latter construction is becoming extremely popular,especially a rigid material known as fiber reinforced polyester resin(FRP) that comprises glass or other type fibers embedded in a curedpolyester resin thermosetting plastic. This construction is not onlyinexpensive, but FRP materials are chemically inert, resistant tocorrosion and hydrolytic degradation, relatively insensitive to thermalchanges, and have other features which make them desirable for use whereheavy occupant traffic is in existence. Full chair support 9 is termedfull support" because it extends fully around the chair including theback, seat and portion joining the two; this is in contrast to a partialsupport that includes only a portion of the back, seat, or portionjoining the two. Full chair support 9 is fastened to pedestal l by mostany conventional means, one form shown here as countersunk machinescrews 11 that pass from support 9 into pedestal l. Full chair support 9terminates at its periphery in flared edge 13 which comprises in crosssection a rearwardly directed gentle curve. Flared edge 13 performs anumber of separate functions; it is the connecting portion of full chairsupport 9 to the replaceable seat insert of this invention and, inaddition, the curvature of edge 13 provides the periphery of support 9with additional rigidity. Moreover, flared edge 13 being a rearwardlydirecting curve places the edge of full chair support 9 out of contactwith an occupant seated in the chair so as to reduce the possibilitythat he or she would snag their clothing on it as well as lowering theincidence of wear on the clamping means.

Positioned on full chair support 9 is seat insert 15 of this invention.Insert 15 is contoured to cover all of full chair support 9 includingthe back and bottom portion thereof so that the term seat insert will betaken hereafter to mean a unitary structure including the back, sides,and bottom portion of a chair support.

Referring to FIG. 2, there is shown in combination a rigid yet flexiblebase 17 that conforms to the contour of full chair support 9 and whoseoutline conforms to the nonflared outline of chair support 9. This isparticularly important to the operability of insert 15 because, as willlater be seen, the size of base 17 must be maintained at less than thefull, flared outline of full chair support 9 to permit the othercomponents of insert 15 to function as designed. Atop base 17 or, inother words, on the opposite surface of base 17 from that restingagainst chair support 9, is cushion layer 19 that comprises a relativelythin layer of open-celled flexible foam in bonded adherence with base17. As will be described later in more detail, it is imperative thatcushion layer 19 be made of an open-cell foam. Cushion layer 19 isadhered to base layer 17 by conventional cements or adhesives, thepreferred type being a contact-type adhesive. Atop cushion layer 19 isnonwrinkling and nontearable cover layer 21 that comprises afabric-backed expanded sheet of flexible polymeric material that isadhered by its fabric-backed side to cushion layer 19 by an adhesive andthat is uniformly slightly larger in area than base 17 and cushion layer19 so as to provide an overlapping strip 23 that extends slightly beyondthe periphery of base 17 and cushion layer 19. Onto strip 23 is joinedresilient clamping means 25 that is snapped into anchoring engagementwith flare edge 13 of chair support 9.

Base 17 is termed ,rigid yet flexible to denote that while it is nottotally rigid, it is far short of being considered flexible. Primarily,base 17 is a rigid plastic material that may be formed such as by vacuumforming to the contour of full chair support 9. Preferable in thisrespect is a vacuum-formable thermoplastic material known asacrylonitrile-butadienestyrene (ABS) resin because of its low cost,lightweight, and easy formability. The thickness of base 17 should besufficient so that the particular plastic is restrained from memorydeformation or reversion to its former shape and should not be so thickthat it will crack under vacuum forming in the areas of high curvatureor deep draw. In respect to the ABS resin, it

hasbeen found that a 50 mil thick sheet of resin is both easily vacuumformed and is sufficient to overcome memory deformation. At the deepestdrawn or deepest contoured portion of base 17 is placed at least one andpreferably'a plurality of apertures 27. These apertures serve a dualfunction: they permit subsequent vacuum forming of cover layer 21 (to bedisclosed more fully later) and, during use of the chair by an 0ccupant,they permit air to escape from collapsed or partially collapsed cushionlayer 19 along the surface between full chair support 9 and the abuttingsurface of pedestal 1. Without apertures 27 in base 17, the occupantgets the uncomfortable feeling that he or she is sitting on a balloonwherein the air entrapped in the cushion layer cannot escape and causesa bulge elsewhere in insert 15; moreover these bulges tend to delaminatecover layer 21 from cushion layer 19.

Base 17 may be formed from a wide variety of materials; in addition tothe preferred material of acrylonitrile-butadienestyrene (ABS) resins,other resins and resinous materials may be used, such an acetyl resins,acrylics, alkyd resins, amino resins, cellulosics, epoxies,fluorocarbons, phenolics,

polystyrene, polyamides, polycarbonates, polyesters, polythenes,polypropylene, and vinyl and vinyl copolymer materials, such aspolyvinyl chloride, vinyl chloride-vinyl acetate copolymers, vinylchloride-vinylidene chloride copolymers, polyvinyl acetate, polyvinylalcohol, polyvinylidene chloride, polyvinyl carbazole, polyphenyleneoxide, phenoxy resins, ionomer resins, poly 4-methyl pentene-l,polyallomers, and the like. Both thermosetting and thermoplasticpolymeric materials are usable as base 17; however, for cost andmanufacturing reasons, vacuum formable thermoplastic materials such asABS resins are preferred.

Cushion layer 19 is comprised of a relatively thin, i.e., onequarter toone inch and preferably i inch thick layer of opencelled flexible foam.It is necessary that the foam be opencelled to enable subsequent vacuumforming of cover 21 by the method of this invention and also to allowair to escape from and return to cushion layer 19 during use of insert15 by an occupant. A preferred material for cushion layer 19 is flexiblepolyurethane foam because of its good aging properties, its resistanceto mildew, etc., however, other materials may be used such asreticulated polyethylene or polypropylene foam, open-celled polyvinylchloride foam, and other similar materials. Cushion layer 19 is adheredto base 17 by an adhesive that is preferably coated on both cushionlayer 19 and base 17. Generally speaking, a contact-type cement ispreferred for this construction.

Over cushion layer 19 is placed cover layer 21 that comprises arelatively thin, i.e., 10-200 mils, nonwrinkling and nontearablefabric-backed expanded sheet of flexible polymeric material that isuniformly slightly larger in area than both base 17 and cushion layer 19so as to provide overlapping strip 23 that extends slightly beyond theperiphery of base 17 and cushion layer 19. Cover layer 21 is adhered tocushion layer 19 by its fabric-backed side; in other words, the fabricbacked side of coverlayer 21 is in contact with cushion layer 19 througha layer or layers of adhesive. Preferred in this respect is also acontact-type adhesive. Note should be made that cushion layer 19 may beof the same area and size as base 17 or may be slightly larger as thereis a small area 27 between the end of base 17 and clamping means 25 forcollapsed cushion layer 19 to occupy. it is essential that cover layer2] be made from a nonwrinkling and nontearable material such as afabric-backed polymeric material so that it will not pucker and foldduring extended use. However, this material while nonwrinkling andnontearable in normal use, i.e., when used on the seat insert at or nearroom temperature, is sufficiently stretchable to permit it to be vacuumor heat formedusually by heating it and subjecting it to pulling andstretching (via vacuum or press head) to conform it to the desiredcontour. In addition, the nonstretchability of cover layer 21 at or nearroom temperature works in combination with clamping means 25 to ensurethat the latter does not loosen during extended use of insert 15. Manytypes of fabric-backed materials may be used, preferred is anylon-backed expanded sheet of flexible polyvinyl chloride plasticbecause of its low cost and the fact that it is vacuum formable.Generally speaking, cover layer 21 is vacuum formed or otherwise formedagainst cushion layer 19 so that in its relaxed position it is tight andnonwrinkled over the entire surface of insert 15.

Nonwrinkling and nontearable (and relatively nonstretchable at or nearroom temperature) cover layer 21 may be comprised of a variety ofmaterials. The fabric layer may be chosen from a variety of weaves suchas knits, straight weaves,

and nonwovens; however, it has been found that the knit weave permits agreater degree of vacuum forming and at the same time provides a highdegree of tear resistance to layer 21 over a wide temperature range; aknit nylon is preferred herein for its strength and ease in vacuumforming. The flexible polymeric material comprising the rest of coverlayer 21 may be chosen from a wide range of materials such as vinylpolymers and copolymers, for example, plasticized polyvinyl chloride,vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinylidenechloride copolymers, vinyl acetate copolymers, polyvinyl alcohol,polyvinylidene chloride, polyvinyl carbazole, and blends of polyvinylchloride with various elastomers such as polyvinyl chloride-nitrilerubber blends, etc. It is preferred that cover layer 21 be of anexpanded type of material, i.e., having at least one foam layer therein.This may conventionally be done by mixing the thermoplastic flexiblematerial, such as vinyl material, with a blowing agent such asazodicarbonamide, azodiisobutyronitrile, benzenesulphonhydrazide,benzonesulphonhydrazide, p-toluene sulfonyl semicarbazide, N,N' dimethylN,N' dintrosoter-phthalamide, trihydrazino triazine, nitrogen, carbondioxide, pentane, fluorocarbon 11, fluorocarbon 12, fluorocarbon 114,and methylene chloride with the thermoplastic, calendering the materialinto a sheet, and then heating it to the point wherein the blowing agentgasifies and forms a cellular structure within the sheet. This isdesired in cover layer 21 so as to provide additional cushioning forinsert and to hide any strike through of the fabric backing. Cover layer21 may be kept nonfoamed (unexpanded) until the time it is vacuum formedduring its adherence to cushion layer 19 and then raised in temperatureto not only gasify the blowing agent within the layer but to smooth outany wrinkles that may have developed in the vacuum forming step. Coverlayer 21 may be pigmented or otherwise colored to show a wide variety ofdecorative colors and in addition may be printed, laminated, orotherwise decorated to any desired design.

Onto strip 23 is joined resilient clamping means 25. One embodiment ofclamping means 25 is shown in cross section in FIG. 3 and comprises asemiflexible extruded polymeric material in the general shape of aquestion mark wherein the major hook-shaped portion 29 is snapped overflared edge 13 and wherein minor hook-shaped portion 31 is sewn orstapled to strip 23. The channel or depression formed by minorhookshaped portion 31 in the outer surface of means 25 permits thestitches or staples to be hidden from view which not only provides for amore pleasing aesthetic appearance but maintainsthe stitches or staplesout of contact with occupants or objects that come against clampingmeans 25 thereby ensuring a longer life for the joining structure, i.e.,stitches or staples. Other embodiments of clamping means 25 are possibleand are fully contemplated herein. Note that strip'23 is folded backupon itself under clamping means 25, as shown in FIG. 2; this is anoptional treatment of strip 23 for it may be trimmed near the stitchesthat pass through minor hook-shaped portion 31; however, trimming strip23 back to this area invites the fabric backing of cover layer 21 tounravel during severe stress. Therefore, it is preferred to merely foldstrip 23 back upon itself at the sewn or stapled portion to ensure amore rigorous affixation to clamping means 25. Preferably, clampingmeans 25 is made of an extruded polyvinyl chloride based material thatis rigid yet flexible however more flexible than base 17, however otherpolymers are usable such as elastomers, e.g., butadiene rubber, isoprenerubber, chloroprene rubber, acrylate-butadiene rubber,isobutyleneisoprene rubber, nitrile-butadiene rubber,nitrile-chloroprene rubber, pyridine-butadiene rubber, styrene-butadienerubber, styrene-chloroprene rubber, styrene-isoprene rubber andelastomer-plastic blends, e.g., nitrile rubber-polyvinyl chlorideblends, urethane rubber-nylon blends, butadiene rubberpolypropyleneblends, etc.

When placing insert 15 onto chair support 9, clamping means 25 must beopened up by bending out major hookshaped portion 29 and snapping itover flared-edge 13. At this time, cover layer 21 is stretched as far aspossible so that it is thereafter held taut, and, due to its fabricbacking will remain taut throughout extended usage. The provision thatbase 17 be kept to the size of the nonflared outline of chair support 9should now be apparent; it permits clamping means 25 to be placed infull clasping contact with flared-edge 13 to achieve a good anchoringposition thereon. Clamping means 25 may be affixed to strip 23 bydifferent means that intertwine in the fabric backing of cover layer 21such as by sewing or by stapling; however, sewing has-been found to bethe most inexpensive as well as one of the most longest lastingconstructions.

In a separate embodiment of this invention, base 17 is roughened on thesurface that is adjacent to cushion layer 19 to enhance the bondingtherebetween. A preferred method of roughening the surface of base 17 isto pass a sheet of base 17 material through a calender or embossingdevice wherein tiny indentations are placed in the surface; this isknown in the vernacular as hair cell embossing. Base 17, cushion layer19, and cover layer 21 may be bonded together by a wide range ofadhesives provided they are compatible with the particular materialsused in these elements. Examples of adhesives usable herein includeacrylic and methacrylic adhesives, bitumen adhesives, casing, celluloseacetate and cellulose caprate adhesives, cellulose nitrate and cyanoacrylate adhesives, epoxy polyamide adhesives, phenolic-polyamide,phenolic-vinyl adhesives, polyamides, polyisobutylenes, polystyrene,poly-vinyl acetyl, polyvinyl acetate, rosin adhesives, epoxies, furanes,melamine-formaldehyde adhesives, oleoresins, phenol-formaldehydeadhesives, phenolic-epoxy, phenolic-neoprene adhesives,phenolic-nitriles, polyester adhesives and polyurethane adhesives,resorcinol-formaldehyde and ureaformaldehyde adhesives, polychloropreneadhesives and acrylonitrile-butadiene adhesives. Specifically preferredin this respect are adhesives known as contact adhesives.

The process of making insert 15 is by a unique combination of stepsdesigned to obtain the benefits of adhesives to lower the material costand manufacturing costs. The first step in making the replaceable seatinsert of this invention is to vacuum form or otherwise fonn base 17from a flat sheet to the contour. of the chair support 9 and then trimthe edges back to the nonflared outline of chair support 9. Prior tothis step of course the surface of base 17, that is to be bonded tocushion layer 19, may have been previously roughened such as by the haircell embossing step heretofore disclosed. After vacuum forming,apertures 27 are placed (drilled or punched) in the deepest drawn orhighest contoured area of base 17. Care must be taken to ensure that theapertures are not too large, such as over h inch in diameter, etc.Thereafter, cushion layer 19 is placed in adherence with base 17. Thisis preferably accomplished by precoating the surface of base 17 and thesurface of cushion 19 (a thin sheet of open-celled flexible foam) with acontact-type cement so that upon joining of the two there is formedimmediately a strong bond therebetween. The edges of cushion layer 19may then be trimmed to the general outline of base 17 or, of course, itmay have been precut to this size. Thereafter, cover layer 21 and thesurface of cushion layer 19 are precoated with a contact adhesive andthen cover layer 21 is vacuum formed onto cushion layer 19 and base 17by utilization of apertures 27. During this step, cover layer 21 may beheated so that it conforms to the contour of base 17 without wrinkling.The edges of cover 21 are trimmed to a uniformly larger size than base17 so as to provide strip 23. Cover layer 21 should be vacuum formed tocushion layer 19 so that the fabric is adjacent the surface of cushionlayer 19. Such a construction permits the wearing surface of cover layer21 to be decorated and otherwise flnished without impairment by thepresence of the fabric layer. Next, clamping means 25 is sewn or stapledaround the edge of cover layer 21 onto strip 23. Thereafter, insert 15comprises the aforementioned construction and may be readily placed ontochair support 9 and clamping means 25, snapped over flared edge 13 ofchair support 9 to place insert 15 in tight anchoring engagement withchair support 9.

What is claimed is:

1. A replaceable seat insert for a flare-edged fully supported typechair comprising in combination:

a. a rigid yet flexible base conforming to the contour and to thenonflared outline of said chair support for positioning against saidchair support, said base having at least one aperture in the deepestdrawn area thereof;

b. a cushion layer comprising a relatively thin layer of opencelledflexible foam adhered to the opposite surface of said base;

c. a nonwrinkling and nontearable cover layer comprising afabric-backed, expanded sheet of flexible polymeric material adhered byits fabric-backed side to said cushion layer and being uniformlyslightly larger in area than said base so as to provide an overlappingstrip of said material extending slightly beyond the periphery of saidbase and said cushion layer; and

d. resilient clamping means joined to said overlapping strip of coverlayer for anchoring engagement with the flare edge of said chairsupport.

2. The insert of claim 1 wherein said base comprises a vacuum formablesheet of thermoplastic polymer.

3. The insert of claim 2 wherein said vacuum formable sheet ofthermoplastic polymer is acrylonitrile-butadiene styrene resin.

4. The insert of claim 1 wherein said base is roughened on the surfacein adherence with said cushion layer to enhance adhesion thereto.

5. The insert of claim 1 wherein said cushion layer is adhered to saidbase with a contact-type adhesive.

6. The insert of claim 1 wherein said cushion layer comprises a flexiblepolyurethane foam.

7. The insert of claim 1 wherein said cover layer comprises a vacuumformable sheet of nonwrinkling and nontearable expanded vinyl polymer.

8. The insert of claim 7 wherein said cover layer comprising a vacuumformable sheet of expanded vinyl polymer is backed with a knittedmaterial.

9. The insert of claim 8 wherein said knitted material is a nylon knitmaterial.

10. The insert of claim 1 wherein said cover layer is adhered to saidcushion layer with a contact-type cement.

11. The insert of claim 1 wherein said resilient clamping meanscomprises a polyvinyl chloride-based extrusion in the general shape of aquestion mark wherein the major hookshaped portion clasps the flarededge of said chair support and wherein said minor hook-shaped portion isjoined to said cover layer.

1. A replaceable seat insert for a flare-edged fully supported typechair comprising in combination: a. a rigid yet flexible base conformingto the contour and to the nonflared outline of said chair support forpositioning against said chair support, said base having at least oneaperture in the deepest drawn area thereof; b. a cushion layercomprising a relatively thin layer of opencelled flexible foam adheredto the opposite surface of said base; c. a nonwrinkling and nontearablecover layer comprising a fabric-backed, expanded sheet of flexiblepolymeric material adhered by its fabric-backed side to said cushionlayer and being uniformly slightly larger in area than said base so asto provide an overlapping strip of said material extending slightlybeyond the periphery of said base and said cushion layer; and d.resilient clamping means joined to said overlapping strip of cover layerfor anchoring engagement with the flare edge of said chair support. 2.The insert of claim 1 wherein said base comprises a vacuum formablesheet of thermoplastic polymer.
 3. The insert of claim 2 wherein saidvacuum formable sheet of thermoplastic polymer isacrylonitrile-butadiene styrene resin.
 4. The insert of claim 1 whereinsaid base is roughened on the surface in adherence with said cushionlayer to enhance adhesion thereto.
 5. The insert of claim 1 wherein saidcushion layer is adhered to said base with a contact-type adhesive. 6.The insert of claim 1 wherein said cushion layer comprises a flexiblepolyurethane foam.
 7. The insert Of claim 1 wherein said cover layercomprises a vacuum formable sheet of nonwrinkling and nontearableexpanded vinyl polymer.
 8. The insert of claim 7 wherein said coverlayer comprising a vacuum formable sheet of expanded vinyl polymer isbacked with a knitted material.
 9. The insert of claim 8 wherein saidknitted material is a nylon knit material.
 10. The insert of claim 1wherein said cover layer is adhered to said cushion layer with acontact-type cement.
 11. The insert of claim 1 wherein said resilientclamping means comprises a polyvinyl chloride-based extrusion in thegeneral shape of a question mark wherein the major hook-shaped portionclasps the flared edge of said chair support and wherein said minorhook-shaped portion is joined to said cover layer.